One idea that has been rolling around in my head lately has been the concept of Extensible Modules (EMs) for HLA Adventure. What I mean by EMs would be the ability for the main game (hlaadv.hla) to load "add-ons" to the core game itself:

Of course, these are just examples; you could theoretically add on any number of different modules at game start up, making it a completely different game each time you play.

The EMs could be small files with a ".emd" extension, which would
have equates, variables, nouns, verbs, or anything else necessary to add on to the existing game. Then the main file (hlaadv.hla) could load these modules into the game environmnent itself. Sort of like how "Elder Scrolls III: Morrowind" does it.

The EMs could also add-on the ability to play the game online with several different people, perhaps adding Guilds to the game. Anything would be then possible with this game, and people all over could develop (and/or compile) their own version of "HLA Adventure" for others to download and enjoy on any number of different operating systems.